Snow Storm Report Card, an Abysmal Snowpack, and a Look Ahead

Last Thursday, I issued snowfall forecasts for several communities on Vancouver Island and across the Lower Mainland. I think it's fair I'm held accountable to these numbers, since they help build my reputation in the weather industry (plus, there's nothing like learning from your own mistakes!). 

----------------------------------------------------------------------------------

The Report Card

Vancouver Island

Campbell River:

  • Amount forecasted: 10-15 cm
  • Total accumulation: 16 cm (YBL) 

Grade: B+

Comments: As one of the communities I expected to get the most snowfall did in fact get some of the highest accumulations in the province, I can't give myself an A letter grade for a number of reasons:

1) I wasn't clear there would be a wide range of snowfall totals. Closer to Georgia Strait and downtown Campbell River 5-10 cm was much more common

2) Next forecast I'll work to convey the range a bit better, expecially when mixing of precipitation is expected along the immediate coast

For your information, School District 72 closed ALL schools in the district for the last day before winter break, and I wholeheartedly agree with their decision, but others in the community weren't sharing the same sentiment:

Comox:

  • Amount forecasted: 5-10 cm
  • Total accumulation: 5 cm

Grade: B+

Comments: Again, problems with some mixing of precipitation along Georgia Strait prevented this community from reaching 10 cm. 

Port Alberni

  • Amount Forecasted: 5-10 cm
  • Total accumulation: 5 cm

Grade: B+

Comments: A touch on the higher side for in the valley, but more appropriate for inland sections and over the mountain passes. 

Nanaimo:

  • Amount forecasted: 5-8 cm
  • Total accumulation: 5 cm

Grade: A-

Comments: Now this is where I expected a significant snow shadow effect and more mixing along the coast, and it reflected in the final amounts.

Victoria: 

  • Amount forecasted: 2-5 cm
  • Total accumulation: 12 cm (YYJ)

Grade: B- 

Comments: Yes, 12 cm of snow fell at Victoria International Airport before turning to rain, but the airport is situated away from the coast and more inland than downtown
Victoria. Most downtown locations saw less than 5 cm of snow with much more mixing reported.

Lower Mainland

Vancouver

  • Amount forecasted: 5-15 cm
  • Total accumulation: 10-15 cm

Grade: B+

Comments: My forecasted amounts were a little conservative, and was influenced a little bit by other meteorologists low-balling the amounts. I was confident in 10-15 cm of snow for the Vancouver area, but was swayed to give a wider range. Next time, I'll stick to my gut feeling, which was inherently a bit riskier.

North Vancouver:

  • Amount forecasted: 10-15 cm
  • Total Accumulation: 14 cm (offical Environment Canada amount)

Grade: A

Comments: Spot on. Most reports from North Vancouver were in the 10-15 cm range. 

YVR:

  • Amount forecasted: 5-8 cm
  • Total accumulation: 10 cm 

Grade: C+

Comments: Fell outside the given range. Several computer models suggested less than 10 cm, especially for the southern areas such as Richmond, but the strong NW jet stream brought more snow streamers off of Georgia Strait late in the morning. 

Abbotsford

  • Amount forecasted: 5-10 cm
  • Total accumulation: 10 cm

Grade: A-

Comments: Fairly good estimate, as I was confident the community would see approximately 5 cm less than the North Shore and Vancouver. 

Final GPA: 3.3 

 

END.

----------------------------------------------------------------------------------

How well did the computer models fair predicting this event? In handling the uncertainties they predicted this snow fall event 4-5 days out with high resolution computer numerical weather prediction techniques. The UW-GFS in particular did a very fine job with this event, and stuck to its guns. We know can put a bit more confidence in high resolution weather models during these marginal snow/rain events.

A tweet by meteorologist Scott Sistek show just how accurate the computer models were for the predicted snowfall during the Friday morning commute: 

When people often complain about weather forecasts they fail to understand how computer models predict the wether, and how there's room for ample amount of error. 

On Scott's recent blog he eloquently phrased these limitations:

The way the models work now is we put in all of the current weather observations across the globe and then the magic begins -- it's been decades of research to create and tinker with the incredibly complex mathematical equations needed to simulate the dynamics of the atmosphere. 

When you think about just how much air is on the planet -- the surface area of Earth is roughly 15.7 million miles and the troposphere, which is basically where our weather occurs, extends from the ground to roughly 40,000 feet (or roughly 7 1/2 miles) high. That's an incredible playground for weather to be created and move around. 

To have a perfect computer model, we would need to know what is going on at every parcel of air at a given moment, have a perfect terrain map of every inch of the globe, and then have the perfect mathematical equations to calculate that data, and account for every nook and cranny on the planet that could affect the data. 

We don't have enough computer power to simulate every parcel of air, plus it's impossible to know the exact meteorological makeup of every single molecule of air on the planet, so we have to improvise a bit. Thus, forecast models aren't perfect -- as we've seen times before -- and likely never will be (at least in our lifetimes) but the fact that we can get pretty close, considering the challenge, is quite a testament to human ingenuity. We were essentially able to predict the future a few days in advance. Try doing that with other parts of our lives. 

Read more from Scott Sistek's weather blog, Partly to Mostly Bloggin' here.

Next blog I'll be focusing in on our abysmal snow pack, and take a look ahead the next 7-10 days to get a better picture at the medium range outlook for our ski resorts. 

Absolute Abysmal 500 mb setup for any substantial alpine snow. Where's the zonal flow?! Massive ridge again poised to form over southern BC. 

Absolute Abysmal 500 mb setup for any substantial alpine snow. Where's the zonal flow?! Massive ridge again poised to form over southern BC. 

In summary, it's looking terrible! Not what skiiers want to hear, and it breaks my heart to have confidence that by the new year Mt. Washington will have grass reappearing through their paltry snow pack. 

Think snowy thoughts (for the mountains anyway!), and have a happy holiday everyone. Thanks again for your support. 

#50shadesofVan